A short man with a long list of health problems was repeatedly punched by cops and zapped with a stun gun until he passed out, a video obtained by the Daily News shows.

Police barged into a Staten Island apartment on the afternoon of Sept. 28 on a domestic violence call and confronted William Colon — all 4 feet 8 inches and 85 pounds of him — on his birthday.

As Colon, 24, begged the officers to tell him why they were there, they grabbed him and threw him on a bed, according to a cell phone video taken by his brother.

Cops barged into a Staten Island apartment on Sept. 28 responding to a domestic violence call and Tased William Colon (Obtained by Daily News)

“I was trying to ask them, ‘What did I do?’” Colon, who has no criminal record, told the Daily News in an exclusive interview. “I was very scared. I suffer from social phobia. I was very confused.”

The footage shows cops forcing him onto his stomach, yanking his arms behind his back and handcuffing him. A burly officer named Vincenzo Trabolse then appears to punch him hard at least three times in the ribs and kidney.

Trabolse also zaps Colon with a stun gun until he falls limp.

Colon is afflicted with a range of health issues that he claims have made him frail. He says he has Mauriac Syndrome, an illness related to diabetes that causes dwarfism. He is also asthmatic, has curvature of the spine and has an intestinal disorder.

Three years ago, he developed heart problems and says he had to quit his job as a clerk at a local Subway sandwich shop.

“I was shocked at the sheer amount of brutality that the officers inflicted on him,” said lawyer Chris Pisciotta of the Legal Aid Society. “He was handcuffed. He wasn’t posing a threat. I don’t understand the lack of humanity of it.”

The Staten Island district attorney’s office is looking into the incident.

“We understand there are questions regarding police conduct in this situation and we can assure the public we will continue to review all evidence and investigate that matter, but have no further comment at this time,” said a spokesman for DA Michael McMahon.

The call that brought police to the Cotter Place home in Richmond Town came from a neighbor who said he heard arguing from the apartment. Colon says he and his girlfriend Lissette Torres were arguing because she wanted to take back the birthday gifts she gave him. Colon’s brother Jazz escorted her out, and at some point the two got tangled up and fell, his lawyers said.

Colon, who was charged with assault and resisting arrest, punched Torres in the face, according to the criminal complaint. But Colon says, “I never touched her.”

Pisciotta said cops arrived and forced their way into the home without explaining why they were there. “The officers said, ‘Open the door or we’ll blow it in,’” the lawyer said. “William says, ‘We don’t need you.’ ”

William Colon (center) and his mother, Sonia Adorno, with Legal Aid Society Attorney-in-Charge Christopher Pisciotta. (Byron Smith / for New York Daily News)

Within minutes, eight to nine officers surround the bed, the video shows.

“His brother Jazz is trying to get the cops to calm down, he’s telling them about his ailments,” Pisciotta explained. “He’s saying, ‘Don’t hurt him.’ ”

Colon was briefly hospitalized after the clash.

“When they Tased me, my blood sugar skyrocketed,” Colon said. “I was very nauseous and pale and vomiting. They thought I was going to go into a diabetic coma. I had to go for X-rays. My body was sore and bruised.”

A police official said Colon was only medically treated for a scratch on his shoulder.

“The majority of the time he was in the hospital was for psychiatric observation because he had a history (of psychiatric issues),” the official said. “We have eight body-worn camera videos which support our report. And you can hear the brother saying, ‘Stop fighting, stop fighting, don’t resist’ the whole time.”

Chief Patrick Conry, an NYPD spokesman, said the department is “ aware of the incident and there is an open internal affairs investigation.“

McMahon’s office defended the charges against Colon.

“This is a case where the police responded to a domestic violence call where a woman suffered clear and obvious injuries to her face,” the spokesman said. “Justice requires that we take that matter seriously, which we do in all domestic violence cases.

But Torres told The News on Sunday that cops threatened her with arrest if she didn’t sign a complaint against her boyfriend of four years.

“They kept trying to get me to write a statement. I said I didn’t want to press charges,” she said. “They told me I was going to get locked up for vandalizing the house if I didn’t. I was frightened. I didn’t want to get arrested. They told me what to write word for word.”

Since then, Torres claims, police have repeatedly visited her home and work and pressured her not to drop the charges.

Pisciotta says prosecutors wrote out a complaint claiming that Colon screamed obscenities at the officers. But, he said, the video doesn’t support that.

“They inserted highly inflammatory language that he was cursing all during this time, but when you watch the video he’s not saying those things,” he said.

The DA’s spokesman said the diatribe was caught on body camera footage after Colon was taken out of the apartment.